Canopy leaf area index and understory plant diversity

Most vegetation management activities in longleaf pine savannas—such as forest stand thinning, roller chopping, herbiciding, and prescribed burning—are aimed at reducing overstory basal area and shrub encroachment (the products of past fire suppression), with the ultimate goal of enhancing herbaceous understory cover and species richness.  High herbaceous cover in longleaf pine savannas is broadly associated with high levels of endemism as well as the habitat requirements of many important animal species. Studies have shown that reduction of woody cover in longleaf systems is correlated with increased herbaceous cover and richness, a phenomenon due in part to canopy cover reduction and the associated increase in light penetration and decrease in leaf litter accumulation, which suppresses understory growth.  In this study, we are examining the relationships between canopy cover (as measured by Leaf Area Index (LAI)) and a variety of overstory, midstory, and understory parameters, in order to determine whether LAI shows strong enough correlations with vegetation parameters to be used as a surrogate for direct vegetation measurement in longleaf pine savannas.